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Re: vacuum in pg9beta4 much slower than in 8.4

From: Greg Smith <greg(at)2ndquadrant(dot)com>
To: Mario Splivalo <mario(dot)splivalo(at)megafon(dot)hr>
Cc: pgsql-testers(at)postgresql(dot)org
Subject: Re: vacuum in pg9beta4 much slower than in 8.4
Date: 2010-08-16 06:44:34
Message-ID: 4C68DE52.70001@2ndquadrant.com (view raw or flat)
Thread:
Lists: pgsql-testers
Mario Splivalo wrote:
> I understand that VACUUM FULL in 9.0 copies all the data, but is it OK 
> that plain vacuum in 9.0 is slower than in 8.4?

It should be faster for tables with a lot of junk in them, but the new 
VACUUM FULL is likely to be slower for ones that are already clean.  
Note that one thing to be aware of is that depending on where you got 
your 9.0 from, it may be compiled with debugging and assertion calls 
that can slow certain operations down quite a bit.  If you try this at a 
command prompt:

postgres=# show debug_assertions;
 debug_assertions
------------------
 on

And that's on, you can expect that copy of 9.0 to be significantly 
slower at a number of things than a similar 8.4.

-- 
Greg Smith  2ndQuadrant US  Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com   www.2ndQuadrant.us


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